Watch out for the Tiny URL's they are dangerous and everywhere.. Don't click a link unless it starts with FACEBOOK.COM that is a sure thing its a facebook link and not a link to a virus or worm. Watch out for children on this site many claim they are older than what they are. Its easy for them to lie, but Its up to the Parent to monitor their child's internet usage. Lets keep it clean and safe for all..
default settings are in fact all set as to share your own material/ pictures/ information etc with anyone, and poss use it without your knowledge or approval, you got to go into every single application and privacy setting to change it to your own liking.